The scale of hydropower transmission across provinces has expanded dramatically along with the operations of a batch of giant hydropower plants in mainstreams of large basin rivers such as Jinsha River, Yalong River and Lancang River in recent years. Now the maximum transmission capacity exceeds 68GW, which means the southwestern hydropower has been an important power source for the recipient power grids. These southwestern hydropower plants and local ones in recipient regions form a very complex interprovincial hydropower system to meet the electricity demands such as power supply and load regulation. It brings new challenges and difficulties to the operation and management of power grids. The hydropower plants located in southwest and east regions usually own respective peculiarity in the aspects of geography, weather, hydrology, etc., which easily leads to greatly different runoff. Moreover, the coupled hydraulic and electric connections impose additional difficult on the problem description and solution. On the other hand, the interprovincial hydropower system needs to meet discrepant operation requirements of power grids and power plants. Specifically, coordinating electricity production over a long period of time and peak power in daily operation is just a primary and new challenge.
More and more attention has been paid to the study of trans-provincial and trans-regional hydropower scheduling with quickly increasing scale of ultra high voltage direct current power transmission. Some researches focused on the operations of cascaded hydropower plants serving multiple provinces. For instance, the hydropower plants on the mainstream of Hongshui River supplies electricity to Guangdong Province and Guangxi Province. The downstream hydropower plants on Jinsha River provide electricity for Guangdong Province and Zhejiang Province. A few studies placed emphasis on the power allocation among multiple power grids under a central dispatching authority (which is usually regional power grids). These previous literatures mainly concern with the optimization allocation of large-scale southwestern hydropower and operations of hydropower plants considering complex load demands from multiple power grids. Little attention is paid to the joint operations of southwest hydropower plants and local ones in recipient regions, and the consideration of operation requirements with two coupled temporal scales. This problem is a technical bottleneck of large-scale hydropower transmission and distribution in China. There is an urgent need for feasible and practical theoretical method and technology.
The invention derives from the National Natural Science Foundation of China (91547201, 51579029), which is based on an actual UHVDC transmission project that is Xiluodu provides electricity for Zhejiang Province. It simultaneously takes into account the monthly and hourly generation scheduling. A new method for the long-term operations for interprovincial hydropower system with peak-shaving demands is developed.